The invention relates to nuclear medicine, and more particularly relates to nuclear medicine studies of patient organs, such as the heart. In its most immediate sense, the invention relates to determination of the depth of, e.g., the patient's heart within the body.
It is advantageous for a diagnostician to know the depth of an organ which is the subject of a nuclear medicine study. For example, in nuclear medicine studies of renal function, physicians evaluate renal function by conducting a planar image study and comparing uptake of radioisotopes with results that are tabulated by body size and depth of the kidney within the patient.
Such depth information cannot easily be determined from planar nuclear medicine image data. If such depth information is to be obtained using SPECT data, it is necessary to conduct a second study, and SPECT studies are time-consuming and expensive.
It would be advantageous to be able to obtain organ depth information from planar nuclear medicine image data, without the need to conduct an additional SPECT study.
Accordingly, one object of the invention is to permit organ depth information to be obtained from planar nuclear medicine image data.
Still a further object is, in general, to improve on known methods and apparatus in nuclear medicine.
In accordance with the present invention, a planar image of the organ of interest is acquired, using a focussing collimator, at two known and different heights. The result of this is two images which differ only in the degree of magnification. The method and apparatus disclosed in the above-referenced parent application is then used to automatically determine, in each of the images, an anatomic landmark related to the organ of interest. Since the focal length of the collimator and the heights of the collimator are known, the difference between the size of the landmark in the two images permits the depth of the organ to be determined using simple geometrical relationships.